Bipolar Integrated Technology, Inc.

Jay D Lessert

Gregory F Taylor

James R Peterson

Bob Elkind

In a high-speed binary multiplier circuit, the multiplicand is segmented into a series of 8-bit slices and the multiplier is modified-Booth recorded into 3-bit groups. The corresponding partial product terms are reduced in a regular array of small carry-save adder (CSA) cells. Iterative use of the CSA array provides the Wallace tree function in one-seventh the chip area or number of adders of a conventional implementation. The multiplier and divider are pipelined internally, driven by a fast, two-phase internal clock that is transparent to the user. The internal clock stops and restarts upon loading new operand and instruction data to synchronize the internal clock to the system clock. Other aspects of the invention include two-speed internal clocking for operation and testing, two-node clock stopping and distributed buffering of system clock signals.

Floating point processor with internal free-running clock

In a high-speed binary multiplier circuit, the multiplicand is segmented into a series of 8-bit slices and the multiplier is modified-Booth recoded into 3-bit groups. The corresponding partial product terms are reduced in a regular array of small carry-save adder cells. Iterative use of the CSA array provides the Wallace tree function in one-seventh the chip area or number of adders of a conventional implementation. The multiplier is pipelined internally, driven by a fast, two-phase internal clock that is transparent to the user. The internal clock stops and restarts upon loading new operand and instruction data to synchronize the internal clock to the system clock. Other aspects of the invention include high-speed absolute value subtract circuitry for exponent calculations and normalizing floating point results.

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Portland, OR, United States of America

Jay D Lessert